1. Field of the Invention
This invention relates to a tabbed and pleated cellular material and method for the manufacture thereof and more particularly to a window covering which contains this tabbed and pleated cellular material.
2. Description of the Prior Art
There are two basic types of folded window coverings. A first pleated type consists of a single layer of corrugated material. The other is a more complex cellular type where pleated layers are joined or folded strips are stacked to form a series of collapsible cells. This latter type is known to have favorable thermal insulation properties because of the static air mass which is trapped between the layers of material when the cells are in the expanded position. The single-layer type, on the other hand, is favored for its appearance in some cases, and is less expensive to manufacture. There is also a tabbed single layer of corrugated material which is disclosed in my U.S. Pat. No. 4,974,656. The tabbed single layer of pleated material has been sold in window coverings and been commercially successful. Consequently, there is a market for a window shade made with a tabbed cellular material.
There are two basic approaches to making cellular products and tabbed panels from a roll of fabric material. The first method pleats or bonds the material transverse to the length of the roll and the second method pleats or bonds longitudinally along its length.
The output of the transverse method cannot be wider than the roll width of the original material. The longitudinal method is limited in the types of patterns that can be printed on the material because alignment is random. The transverse methods have been limited to a single layer, a single tabbed layer or a triple layer where there are three continuous surfaces that create a panel of double cells.
There is a need to have a transverse process that can make a panel of single cells. There is also a need to increase the speed of production output of single, double and triple layers.
There are several methods of producing the cellular shades. Most similar to the pleated, single-panel method is Anderson U.S. Pat. No. 4,685,986. This method joins together two single-panel pleated lengths of material by adhesively bonding them together at opposing pleats. Other methods depart from this Anderson patent by joining together a series of longitudinally folded strips, rather than continuous sheets of pleated material. Such methods are shown in Colson U.S. Pat. No. 4,450,027, and in Anderson U.S. Pat. No. 4,676,855. In the Colson patent, strips of fabric are longitudinally folded into a U-shape and adhered on top of one another, whereas in the Anderson patent these strips are Z-shaped and are adhered in an interlocking position.
In U.S. Pat. No. 5,043,038 Colson discloses a method of cutting a honeycomb structure longitudinally to divide them into two tabbed single layer pleated panels. That honeycomb structure was formed from U-shaped strips as taught in Colson's U.S. Pat. No. 4,450,027 by a process of winding the foldable material around a base apparatus, applying glue to one face of the material and adhering each layer to the adjacent layer. This method tends to cause the tab to wrinkle because the stack is wrapped on a slightly curved mandrel. Also, because the material layers are wound in a stack, the length of the panels of final product are limited to the height of the wrapped stack and the ends of the stack are wasted.
Another method for making cellular shades is disclosed in U.S. Pat. Nos. 5,015,317; 5,106,444 and 5,193,601 to Corey et al. In that process fabric material is run through a production line that first screen prints the fabric and then applies thermoplastic glue lines at selected intervals. The fabric is then pleated, stacked, and placed in an oven to both set the pleats and bond the material at the glue lines.
There is a need for a method to utilize the current transverse processing equipment technology to make a larger variety of single and multi-layer panels at a faster rate.